1. Field of the Invention
This invention relates to a machine for the filling of containers, in particular for the filling of bottles and to the relative filling method.
2. Discussion of the Background
The bottling and the packaging industry in general performs a series of successive operations for the purpose of filling containers such as bottles, vials, and cans with foodstuffs, cosmetics, chemical and pharmaceutical products, oils and paints, glues, detergents and other materials.
In particular, the foodstuffs and wine industry usually include the preliminary washing, rinsing and sanitizing operations for the bottles to be filled.
Then, the filling operation may be performed in different ways, depending on the products destined to fill the containers; for the filling of gaseous and sparkling wines, for example, the filling machines in use are of a so-called isobaric type, because the pressure of the container is the same as that of the storage tank holding the wine to be filled. A balanced pressure is therefore established between the holding container and the bottles, while evacuating the inside air to the outside. A first phase is therefore performed by pre-evacuating the air contained in the bottles while aspirating the same with a vacuum pump from a small tube placed next to the neck of each bottle.
EP-A-597161, for example, dislcoses a known filling machine of the isobaric type according to the preamble of the invention.
Said known machine essentially consists of a horizontal cylindrical container, whose lower section mounts a series of particular filling taps. The wine level in the tank is regulated by a float which governs, as the level changes, the opening and closing of a vent opposite to the inert gas chamber above the wine, resulting in a constant liquid level.
The filling taps are generally composed of a spout with two concentric tubes, one originating in the lower section of the tank draining the wine to the bottle and one leading to the inert gas chamber to allow discharging the air contained in the bottle.
The air and wine tubes of each spout are actuated respectively by two controlling devices, each of which includes a small spring-loaded piston acting as a true shut-off tap. The pair of small pistons is actuated by the alternating motion of lever fitted with a handle, pressing its two elbows against a bracket which acts, in the lower part of the tap, on the actuating heads of the two small pistons.
The opening of the latter occurs at two separate instants: an air vent opens up first, allowing an instantaneous balancing of the pressure between the gas chamber and the interior of the still empty bottle, thus starting the flow of the wine filling the bottle. Other vacuum-filling machines are known for handling many types of foodstuffs, such as wines, liquors, sirups, fruit-juices, oils and liquid chemicals, shampoos, and cosmetic preparations. These machines work under a slight depression, thus creating a more or less pronounced vacuum in the container aspirating the product, which moves from the main source to the machine tank mounted above the filling section; the liquid volume in the tank is regulated by a float or by appropriate probes.
The containers are lifted toward the filling nozzles on cam-actuated tables and made to tightly fit against the rubber rings of the nozzles. The inside air is gradually expelled as the vacuum is applied; this achieves a substantial seal at the entrance tap, thus preventing any spillage in the surrounding environment; if a container is defective and cannot withstand the vacuum, it cannot be filled and is therefore automatically discarded.
Another type of traditional filling machine is the so-called volumetric or gravity machine, in which the filling occurs by free falling and constant dosing. The product is aspirated from the vat above the machine, immersed in the dosing devices and fed to the containers by the latter.
The machine is equipped with a number of dosing devices, each constituted by a cylinder with an internal piston aspirating the desired quantity of product, whose volume is determined by the diameter of the cylinder and the length of the piston run.
In the isobaric and in the known vacuum-actuated machines, however, the liquid to be bottled flowing through the neck of the bottle comes, while only for a brief period, in the contact with the air contained therein; moreover, the insufflated inert gas crossing the same conduit as the flowing liquid before falling into the bottle mixes with the liquid itself, thus causing some evident oxidising problems and therefore a rapid alteration of the same liquid.
In particular, these negative consequences are extremely important where edible goods with a short conservation span, such as wine, tea, milk and the like are bottled. In this regard and to eliminate this shortcoming, some isobaric machines have been developed which allow for a separate air return from the liquid handled, and can be equipped with a separate tubing for insufflating inert gas to the bottle. However, even the use of these machines cannot eliminate the problem of the presence of a certain volume of oxygen in the neck of the bottle, which remains in contact with the upper layer of the liquid contained therein.
In order to perform the phases of pre-evacuating the air inside the bottles and insufflating inert gas through the neck, it was further proposed to utilise a dedicated tube, fitted on the outside of the filling apparatus and separated from the central liquid feeding tube.
This solution, while advantageous from the viewpoint of an actual absence of product contamination and/or oxidation, poses numerous problems associated with the installation of the machine and the encumbering of relatively wide working spaces.
Moreover, an embodiment of this type amounts to production and operating costs that should rather be minimized.
The use of gravity machines avoids the oxidising problems mentioned above, because the pressure differential existing between the bottle interior and the filling tube is not used to introduce the liquid to the bottle, and the air aspirating step is therefore eliminated. However, these machines do not allow a complete filling process, because they make it impossible to perform the pre-evacuating and/or gas insufflating phases across the neck of the bottle; these operations must in fact, if desired, necessarily be carried out by dedicated systems, with the ensuing production delays and relatively high production costs.